1. Field of the Invention
The present invention relates to a device for attaching and detaching a counterweight of a construction machine.
2. Description of the Related Art
A counterweight (hereinafter sometimes referred to as CW) of a construction machine is normally placed on a support bed projected horizontally from a rear end of a rotating frame of an upper rotating body. The CW is secured to the support bed by means of fixing bolts. The CW is removed when the construction machine is transported, and mounted when working. When the CW is attached or detached, the CW has to be lifted or suspended so as not to interfere with the support bed.
For example, a method for attaching and detaching a counterweight disclosed in Japanese Patent Application Laid-Open No. Hei 7-324354 is known. As shown in FIG. 8a, first, a construction machine 80 is gone up to an inclined bed 81 to incline an upper rotating body 88. Then, an upper portion 84a of a boom 84 and an upper surface portion 85a of CW 85 are connected by a wire rope 87 through a sheave 86a provided on an upper end of a mast 86, and the fixing bolts are removed. As a result, the CW 85 is hung down from the sheave 86a by gravity, and the CW 85 is moved away from the support bed 89.
Next, as shown in FIG. 8b, when the boom 84 is raised up, the wire rope 87 is delivered from the sheave 86a whereby the CW 85 can be dropped off on the ground.
However, in the aforementioned method, a large inclined bed has to be prepared every time the CW 85 is attached or detached. Moreover, there poses a problem that the construction machine is forced to assume the unstable attitude.
Further, since rewinding or hoisting of a wire rope is carried out by boom rasing or lowering operation, it is difficult to locate the CW 85 to the support bed. Moreover, an operator who operates the boom is not able to grasp the suspending condition of the CW 85 from an operating seat. There is a problem that since operation has to be carried out through the aid of a person giving a sign, the work efficiency is poor.
It is an object of the present invention to provide a device for attaching and detaching a counterweight capable of attaching and detaching a counterweight easily and simply to attain the enhancement of the efficiency of attaching and detaching work, and a construction machine having the device.
The construction machine having a device for attaching and detaching a counterweight according to the present invention has the following constitution.
The present invention comprises a lower traveling body; an upper rotating body mounted rotatably on the lower traveling body, the upper rotating body having a support bed standing out from a rear portion thereof; an attaching and detaching device for attaching and detaching a counterweight mounted on the support bed. The attaching and detaching device comprises a telescoping device having a lower end pivotally connected in the vicinity of the support bed, a restiform body hung down through a guide portion provided on the telescoping device, and oscillating means for oscillating the telescoping device around the lower end as fulcrum. The oscillating means displaces the telescoping device extended from a substantially vertical attitude to an inclined attitude when the counterweight is removed or moved downward.
In this case, when the telescoping device is expanded or contracted, the counterweight can be raised or fallen through the restiform body hung down from the guide portion. When the telescoping device is displaced from a substantially vertical attitude to an inclined attitude by the oscillating means, the counterweight can be moved to a position not to interfere with the support bed or the counterweight can be moved upward of the support bed without interfering with the support bed. Because of this, the counterweight can be attached or detached from the support bed by its own exertions and quickly.
Further, since a series of operation are carried out while lifting the counterweight (that is, while maintaining a fixed attitude), it is also easy to locate of the counterweight to the support bed.